usbhs_pkt_pop
struct usbhs_pkt *usbhs_pkt_pop(struct usbhs_pipe *pipe, struct usbhs_pkt *pkt);
pkt = usbhs_pkt_pop(pipe, NULL);
usbhs_pkt_pop(pipe, usbhsg_ureq_to_pkt(ureq));
usbhs_pkt_pop(pkt->pipe, pkt);
pkt = usbhs_pkt_pop(pipe, NULL);